What question did this study set out to answer?

To compare the kinetics of isometric force development following caged ATP activation in tonic and phasic smooth muscles.

October 1, 1989The Journal of General PhysiologyOpen Access

Kinetics of contraction initiated by flash photolysis of caged adenosine triphosphate in tonic and phasic smooth muscles.

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Population

Glycerinated tonic (rabbit trachealis) and phasic (guinea-pig ileum and portal vein) smooth muscles

Comparison

Laser flash photolysis of caged ATP in the… vs Tonic versus phasic smooth muscles…

Design

Preclinical

Authors

KHK. HoriutiOita University Hospital ASAvril V. SomlyoVascular / Pulmonary Vascular YGYale E. GoldmanHeart Failure / Cardiomyopathy

Discussion

Member takes

Implication

Tonic smooth muscle shows slower force kinetics than phasic due to differences in both machinery and regulation; leaves open translation to human cardiovascular physiology.

Key Points

To compare the kinetics of isometric force development following caged ATP activation in tonic and phasic smooth muscles.
Used laser flash photolysis of caged ATP in the presence of Ca2+ at 20 °C to trigger isometric force development from rigor states in glycerinated rabbit trachealis (tonic) alongside guinea-pig ileum and portal vein (phasic).
Pre-activated the regulatory system in selected muscle preparations prior to photolysis using ATP with okadaic acid or thiophosphorylation with ATPγS.
Photolysis of caged ATP produced isometric force with a half-time (t1/2) of 5.4 s in trachealis compared with 1.2–2.2 s in phasic muscles.
Prephosphorylation accelerated force development, yielding t1/2 values of 0.8–1.1 s in trachealis versus 0.20–0.25 s in ileum and portal vein muscles.
Isometric force development followed a sigmoidal time course across all muscles, displaying an initial delay equal to approximately 10% of the t1/2 value.

Structured PICO

Population

Glycerinated tonic (rabbit trachealis) and phasic (guinea-pig ileum and portal vein) smooth muscles

Intervention

Laser flash photolysis of caged ATP in the presence of Ca2+, with or without prior phosphorylation (ATP plus okadaic acid or thiophosphorylation with ATP gamma S)

Comparator

Tonic versus phasic smooth muscles; unphosphorylated versus prephosphorylated muscles

Outcome

Time course of isometric force development (half-time, t1/2)surrogate

Both the contractile machinery and regulatory system are slower in tonic compared to phasic smooth muscles.

Cite This Study

Horiuti et al. (1989) studied this question.

synapsesocial.com/papers/6a7027f653da1ffdb5079d75 https://doi.org/10.1085/jgp.94.4.769

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Implication

Tonic smooth muscle shows slower force kinetics than phasic due to differences in both machinery and regulation; leaves open translation to human cardiovascular physiology.

Kinetics of contraction initiated by flash photolysis of caged adenosine triphosphate in tonic and phasic smooth muscles.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Kinetics of contraction initiated by flash photolysis of caged adenosine triphosphate in tonic and phasic smooth muscles.

Discussion

Member takes

Implication

Key Points

Structured PICO

Cite This Study

Also Consider

Also Consider